Not sure if this is just something I'm completely missing...
I am trying to decide the orientation of an object by the direction it is traveling across 3d space. So in other words, if the object is traveling only on the z axis (say from 0 to -4000) the object would be facing the direction it is traveling. This wouldn't be so hard - the challenging part is if you are going from 360, 240, 0 to 100, 600, 500. This would be a diagonal line. And the even more challenging part to me is if you are interpolating with any kind of curve.
The way I have it set up, I am wanting to animate an object with wiggle(1, 800). With this expression, the object moves with smooth interpolation, and therefore to achieve this goal the object's orientation would have to interpolate at the same rate. I am guessing there is some way to do this through expressions? I know it will be a challenge, because expressions cannot pass on information from previous frames. Is it possible to auto-keyframe based on an expression, and then use the differences in the values to find a vector value, and then calculate the orientation?
I am animating a null object and tying particular to the null. I'm not using a light because it creates problems with using other lights with Particular 2 (the light is accepted not only as the emitter but as a light would normally be accepted). The particle I am using is a custom particle (a few circles precomped). Using it to build a mesh of "strings", but this could be any shape really.
All of this is fine and well; The particle, however, stays oriented to the camera at all times. Is there a way to tie the orientation along the path to define the orientation of the custom particle layer within the particle precomp? I imagine it would require the layer to be 3d within the precomp.